Control wheel assembly for trolleys

ABSTRACT

A trolley control wheel assembly adapted to be fitted to a trolley having a longitudinal axis of travel includes (1) an array of castors; (2) a fixed wheel or wheels adapted to be positioned at or near the load center of the trolley or at or near the center of the array, and (3) bias and damping to provide controlled contact between the wheel or wheels and a surface on which the trolley is intended to travel. The bias damping may jointly comprise a gas strut.

FIELD OF THE INVENTION

This invention relates to a control wheel assembly for a trolley and toa trolley fitted with such an assembly and particularly relates tocontrol wheel assemblies for hand trolleys fitted with castors andincludes, by way of example trolleys for the carriage or transport ofgoods in supermarkets, trolleys for the carriage or transport of baggageat airports, trolleys for the carriage or transport of goods inwarehouses and offices, trolleys for the carriage or transport ofpatients or food or medicines or medical equipment in hospitals andperambulators or “prams”. As is well known, castors are provided ontrolleys to enable the trolley to be propelled in any desired directionindependent of the direction in which the trolley may be apparentlyorientated.

1. Background of the Invention

Trolleys of the above type have a base frame which is usually fittedwith four castors to enable the trolley to be pushed in any directionand manoeuvred in sometimes confined spaces. Such trolleys arenotoriously difficult to control and steer, particularly if any of thecastors becomes worn, dirty or damaged or if the trolley is operated ona sloping, slippery or uneven surface.

2. Discussion of the Prior Art

A number of attempts have been made to overcome the problem ofcontrolling such trolleys. European Patent application No. A2 0 352 647Wanzl Metallwarenfabrik GmbH, discloses a stackable (nestable) shoppingtrolley having four guide castors at the comers of the frame of thetrolley and having one (or more) support castors or wheels located underthe centre of the frame. The support castors or wheels are spring biasedto press onto the ground to prevent the trolley rolling sideways on anincline. The castors or wheels are hinged to move out of the way whenthe shopping trolley is nested with other similar trolleys. AustralianPatent No. 589,046 (European 0 267 817) Ostosvaunuholto Oy, discloses atrolley having four castors and a fifth wheel (or pair of wheels) atabout the centre of the frame of the trolley.

The trolley has a bottom frame having all wheels or castors attached toit in which: the bottom frame is substantially “M” shaped in plan view;the tour castors and the fifth wheel(s) are not coplanar such that e.g.the front or rear castors do not touch at the same time on a flatsurface. The fifth wheel is thus not spring biased. The arrangement isdesigned to overcome the difficulty of steering trolleys which becomesgreater as the load on the trolley becomes greater. Australian PatentApplication No. 42540193, Lloyd discloses a five castor trolley in whichthe fifth “central” castor can be simply automatically locked againstvertical axis rotation during use and unlocked when it is desired tomove the trolley sideways. Australian Patent Application No. 51532/93Feron Investments Limited, primarily discloses a trolley with castors inwhich the axes of the castors may be varied from the vertical in any oneor more of the forward, rearward or sideways directions. Thespecification also discloses the possible use of a fifth castor which isonly disclosed as being situated between the front castors.

Australian Patent No. 640,700 Lovie & Grantham, discloses a castorlockable about the vertical rotation axis similar to Lloyd above.Australian Patent No. 573,843, Kart Gard Internationale, Inc., disclosesa shopping cart security device in which a fifth wheel drops and locksautomatically when the trolley is pushed over a hump which makes thetrolley difficult then to control. British Patent Application No.2,052,399, Cheddar Valley Engineering Limited, discloses a nestabletrolley with a “V” frame and a hinged rectangular base with two fixedwheels on the arms of the “V” at about the pivot between the base andthe frame and two castors on the opposite ends of the base with a fifthcastor at the point of the “V” of the frame. The two castors providestability to the triangular configuration of the fixed “V” frame wheelsand the fifth castor under load. U.S. Pat. No. 4,456,273, McKinnon,discloses a trolley frame of “M” plan configuration in which the twoside arms of the frame can pivot to abut the middle arms of the “M”frame. McKinnon does not disclose a fifth wheel assembly. None of theabove appear to have solved adequately the problem of controllingtrolleys as there is still widespread use trolleys which merely havefour castors and which, after a while become difficult to control andsteer. Whilst the prior art discloses the use of a “fifth” wheelarrangement, none of the prior art discloses or suggests the use of afifth fixed wheel assembly which includes bias means to bias the fifthwheel towards surface on which the trolley is travelling and dampingmeans to control the effect of the bias means or a single bias anddamping means combination.

BRIEF DISCLOSURE OF THE INVENTION

It has unexpectedly been found that the provision of a trolley controlwheel assembly with a combination of damped bias means to a trolleyallows excellent control of the trolley as compared to presently usedtrolleys without such an assembly. The control wheel assembly controlsthe direction of travel of the trolley over and above the influence ofthe castors. The control wheel assembly includes a fixed wheel meanswhich includes a wheel which is able to rotate about it's hub axis butis not able to rotate about a vertical axis as can a castor.

The present invention therefore provides in one preferred form a trolleycontrol wheel assembly adapted to be fitted to a trolley having alongitudinal axis of travel and an array of castors, which assemblyincludes a fixed wheel or wheels positioned at or near the load centreof the trolley or at or near the centre of the array and which includesa bias means and a damping means to provide controlled contact betweenthe wheel or wheels and a surface on which the trolley is intended totravel. The present invention also provides in another preferred form atrolley having a longitudinal axis of travel and having an array ofcastors fitted thereto and a trolley control wheel assembly whichincludes a fixed wheel or wheels positioned at or near the load centreof the trolley or at or near the centre of the array and which includesa bias means and a damping means to provide controlled contact betweenthe wheel or wheels and a surface on which the trolley is intended totravel. The present invention also further provides, in a trolley havinga longitudinal axis of travel and having an array of castors on whichthe trolley can be moved from place to place in the general direction ofthe longitudinal axis of the trolley or otherwise, the improvementswhich comprises the provision of a control wheel assembly, whichassembly includes a fixed wheel or wheels positioned at or near the loadcentre of the trolley or at or near the centre of the array and whichincludes a bias means and a damping means to provide controlled contactbetween the wheel or wheels and a surface on which the trolley isintended to travel. Preferably the load centre of the trolley and thecentre of the array of castors coincide. The force exerted on thecontrol wheel by the damped bias means is not so excessive as to liftany of the trolley castors off the travel surface when the trolley isunloaded. In other words, the force of the bias means must not exceedthe weight of the empty trolley. Preferably, the force of the bias meansis independent of the load on the trolley. Preferably the bias means andthe damping means are jointly provided by a gas strut. Preferably thetrolley has four castors preferably disposed at or near the corners ofthe trolley or disposed effectively at or near the corners of thetrolley. Preferably the array of castors includes four castors.Preferably, in order to facilitate lateral manoeuvring of a trolleythere is preferably provided a lifting means to lift the wheel of thecontrol wheel assembly out of contact with the floor or other travelsurface to enable the trolley to be more readily moved at right anglesto the customary desired direction of movement or travel. 19.Alternatively the invention provides a castored trolley, control wheelassembly, which includes a fixed wheel or wheels or wheel equivalentwhich includes a bias means and a damping means to provide controlledcontact between the wheel or wheels and a surface on which the trolleyis intended to travel. Preferably the bias and the damping are bothprovided by a gas strut.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings there is shown preferred embodiments of theinvention as follows:

FIG. 1 is a schematic perspective view of one preferred control wheelassembly made according to the present invention;

FIG. 2a is a schematic cross-sectional front view of the control wheelassembly of FIG. 1; FIG. 2b is a schematic cross-sectional front view ofa control wheel assembly having two wheels;

FIG. 3 is schematic side view of a trolley including a control wheelassembly according to FIG. 1;

FIG. 4 is a schematic plan view of the trolley of FIG. 3;

FIG. 5 is a schematic partial plan view of the trolley of FIG. 3 withtwo control wheel assemblies according to FIG. 1;

FIG. 6 is schematic side view of a shopping (i.e. “supermarket”) trolleyincluding a control wheel assembly according to FIG. 1;

FIG. 7 is schematic partial plan view of the shopping trolley of FIG. 6;

FIG. 8 is schematic side view of a number of shopping trolleys as inFIG. 6 in a stored or “nested” configuration; and

FIG. 9 is schematic partial plan view of the nested shopping trolleys ofFIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2 there is shown schematically a preferredcontrol wheel assembly 10 made in accordance with the invention. Theassembly 10 includes wheel means 11 (comprising a single wheel in FIG.2a and a pair of wheels, each able to rotate independently, in FIG. 2b)free to rotate only about rotational axis 12, mounted by bracket 13 onto a telescopic member 14 comprising two square tubular sections 15 and16 made such that section 15 is able to freely slide within section 16.Mounted within the telescopic member 14 is a gas strut 17 attached tothe tube sections 15 and 16 by attachment flanges 18. The gas strut 17provides damped bias to the telescopic movement between the tubesections 15 and 16 and thus to the wheel 11. Mounting flange 19 isprovided to permit attachment of the assembly to a trolley (not shown).

The assembly may also include a lifting lug 20, where the assembly is tobe attached to a nestable trolley such as a shopping trolley to permit(as will be described later) the control wheel to be lifted to permit asingle trolley or a group of nested trolleys to be easily manoeuvred ina direction lateral to the normally desired direction of travel. In thecase of a trolley not designed to nest there may be provided a levermechanism (not shown in detail) which can engage lifting lug 20 to raisethe wheel 11 from contact with the floor or travel contact surface. Theassembly may be readily fixed to a trolley to provide excellent controlof the trolley in the longitudinal direction of the trolley, that is inthe direction of travel of the control wheel, whilst still permittingthe trolley to be manoeuvred sideways as required depending on thenature of the floor surface on which the trolley is situated.

Referring to FIGS. 3 and 4 there is shown a trolley 30 including acontrol wheel assembly 10 as described in detail above in relation toFIGS. 1 and 2. The trolley includes a frame 31 provided with shelves 32and has a base 33 fitted with an array of four castors 34 fixed at ornear the corners of the base 33 as is well known in the art. The controlwheel assembly 10 is mounted at the centre of the array, equidistantfrom each of the castors 34. The control wheel assembly 10 is attachedto the base 33 by means of the mounting flange 19. The control wheelassembly 10 controls the direction of travel of the trolley 30 over andabove any influence of any one or more of the castors 34.

Referring to FIG. 5 there is shown an alternative construction oftrolley 30 as shown in FIGS. 3 and 4, wherein like numbers identify likeparts, in which there are two separately mounted control wheelassemblies 10 a and 10 b attached to the base 33 of the trolley 30. Thedual control wheel assembly controls the direction of travel of thetrolley 30 over and above the influence of any one or more of thecastors 34. Two control wheel assemblies such as have been described maybe necessary if the trolley is carry heavy loads on slippery, polishedor wet and/or inclined surfaces.

Referring to FIGS. 6 and 7 there is shown a supermarket trolley 40having a base frame 41 and a basket 42 with a handle 43 affixed thereto.The base frame includes posts 44 to connect the base frame 41 to thebasket 42. The base frame 41 is in plan view, best seen in FIG. 7, of a“double J” form with one side frame section 41 a of the base frame 41 amirror image of the other side frame section 41 b of the frame. Theframe 41 is fitted with an array four castors 45 affixed at or near eachcomer of the base frame as is well known in the art. The side framesections frames 41 a and 41 b have a control wheel assembly 10 (asdescribed in detail above with reference to FIGS. 1 and 2) affixedthereto by means of the mounting plate 19 near their ends 46 a and 46 b.The ends 46 a and 46 b of the side frame sections 41 a and 41 b on atrolley are turned down for reasons which will become apparent in thefollowing. The control wheel assembly, as previously being biaseddownwards, controls the direction of travel of the trolley 30 over andabove the influence of any one or more of the castors 34.

Referring to FIGS. 8 and 9 there is shown a number of shopping trolleys40 (40 a, 40 b, 40 c,. . . ) which are as described in relation to FIGS.6 and 7, and in which like numbers identify like parts. A group oftrolleys 50 are nested together (as is the usual requirement for suchtrolleys) for compact storage and transport. Each of the trolleysincludes, as described above in relation to FIGS. 6 and 7, a controlwheel assembly 10. The ends 46 a and 46 b of the side frame sections 41a and 41 b on the trolleys are turned to slope downwards to form a rampconfigured so that the ramp on one trolley engages the lifting lug 20 onanother trolley and raises the wheel of the control wheel assemblyagainst the action of the bias means to lift the control wheel fromengagement with the ground or travel surface. This allows the group ofshopping trolleys to be moved as a whole without the hindrance of thecontrol wheel assemblies of all of the trolleys in the group.

The trolley of FIGS. 3 and 4 may preferably include a lever mechanism(not shown) to optionally engage a lifting flange to lift the wheel ofthe control wheel assembly from contact with the floor, ground (or othersurface on which the trolley is to be used) so that the trolley can bereadily moved sideways to enable the trolley to be parked in a confinedspace, for example.

Whilst we have described preferred embodiments of the invention hereinit will be realised by those skilled in the art that many variations maybe made to the invention as particularly described without departingfrom the scope of the invention broadly disclosed. For example it willbe appreciated that the control wheel assembly of the invention does nothave to be positioned exactly at the centre of the array of castors. Thecontrol wheel assembly should, for ease and evenness of control, belaterally in the middle of the trolley. The position of the controlwheel assembly longitudinally on the trolley is of lesser importance andmay be determined by the load centre of the trolley or by the centre ofthe array of castors. Preferably the two points coincide although forpurpose built assymetrical trolleys, this may not be the case. Thecontrol wheel is, as previously disclosed, “fixed” in that the wheelcannot rotate about a vertical axis as a castor is able. The wheel isable to rotate about it's normal horizontal rotational axis and is“fixed” to do so in the direction in which it is normally desired thatthe trolley proceed. In most cases in a trolley having a substantiallyrectangular base or castor array, the wheel is fixed and able to rotatein the longitudinal direction (as against the transverse direction) ofthe trolley and is at the centre of the array of castors.

What is claimed is:
 1. A trolley control wheel assembly adapted to befitted to a trolley having a longitudinal axis of travel and an array ofcastors having respective castor wheels, said assembly comprising: afixed wheel adapted to be disposed in use on a trolley in a vicinity ofone of a load center of the trolley and a center of the array ofcastors, and a strut assembly independent of the castors and operable toprovide controlled contact between the fixed wheel and a surface onwhich the trolley is intended to travel, said strut assembly including afirst part connected to a member which rotatably supports the fixedwheel and a second part which is fixed in use to the trolley, said firstand second parts being telescopically guided with respect to each otherand being configured to prevent relative rotation of said first andsecond parts to thereby maintain the fixed wheel in a fixed directionwith respect to the trolley when in an in use position on a trolley. 2.A trolley control wheel assembly as claimed in claim 1, wherein saidfirst part and said second part are polygonal sections.